1. Field
Exemplary embodiments of the present invention relate to a semiconductor design technology and, more particularly, to a voltage generator for generating internal voltages.
2. Description of the Related Art
Semiconductor devices are supplied with a voltage from an external source. The external voltage rises to its target voltage at a specific rate during initial operations. If the external voltage is directly applied to the internal circuits of a semiconductor device, the internal circuits will likely malfunction because the target voltage is still rising (i.e. has not stabilized). In order to prevent such malfunctions, semiconductor devices perform a power-up operation for guaranteeing stable operation of the internal circuits. The power-up operation includes activating a power-up signal when the external voltage reaches its target voltage level. After the power-up signal is activated and the external voltage stabilizes, the external voltage is supplied to the internal circuits of the semiconductor device.
FIG. 1 is a block diagram of a conventional voltage generator of a semiconductor device.
Referring to FIG. 1, the voltage generator includes a regulator 110 and a charging unit 120.
The regulator 110 receives a first power supply voltage VCCE from an external source and generates a second power supply voltage VCCI that is lower than the first power supply voltage VCCE. The charging unit 120 includes a capacitor and stably outputs the second power supply voltage VCCI using the regulator 110. That is, the charging unit 120 makes the second power supply voltage VCCI steady using the dampening characteristics of the capacitor.
During a power-up section of a semiconductor device, the regulator 110 receives the first power supply voltage VCCE that rises to its target voltage level and generates the second power supply voltage VCCI. The internal circuits of the semiconductor device receive the first and the second power supply voltages VCCE and VCCI and generate various internal voltages, in response to a power-up signal that is activated when the first power supply voltage VCCE and the second power supply voltage VCCI reach a specific level or higher.
During a fast power-up section, that is, if a power-up operation is performed at high speed, the semiconductor device rapidly generates the second power supply voltage VCCI by filling the charging unit 120 with a large amount of current. Accordingly, as the amount of peak current is increased during the power-up section, power consumed by the semiconductor device is increased.